<!doctype html>
<html lang="en">

<head>
    <title>Title</title>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
        integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
    <script src="./grap/gsap.js"></script>
    <style>
        .alert-div {
            width: 400px;
            margin: 0 auto;
            /* transform: translateX(calc(100vw / 2- 50%)); */
            transform: translateY(-100px);
            background-color: crimson;
            padding: 10px;
        }

        .button-x {
            background-color: red;
            margin-left: 80px;
            color: white;
            cursor: pointer;
        }

        .alert-animation {
            animation: alert-start 2s linear forwards;
        }

        .alert-animation-end {
            animation: alert-end 2s linear forwards;
        }

        @keyframes alert-start {
            from {
                transform: translateY(-100%);
            }

            to {
                transform: translateY(100%);
            }
        }

        @keyframes alert-end {
            from {
                transform: translateY(100%);
            }

            to {
                transform: translateY(-100px);
            }
        }
    </style>
</head>

<body>

    <button onclick="handler(event)">确认</button>
    <div class="alert-div" role="alert">
        A simple danger alert—check it out!
        <button class="button-x" onclick="back(event)">x</button>
    </div>

    <script>
        const alertbox = document.querySelector('.alert-div')
        function handler(e) {
            gsap.to('.alert-div',{
                transform:`translateY(100%)`,
                duration:2,
                easing:'linear'
            })
        }
        function back(e) {
            gsap.to('.alert-div',{
                transform:`translateY(-100px)`,
                duration:2,
                easing:'linear'
            })
        }
    </script>
    <!-- Optional JavaScript -->
    <!-- jQuery first, then Popper.js, then Bootstrap JS -->
    <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"
        integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo"
        crossorigin="anonymous"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"
        integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1"
        crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"
        integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM"
        crossorigin="anonymous"></script>
</body>

</html>